To pass across (7)
I believe the answer is:
transit
'to pass across' is the definition.
(synonyms)
This is all the clue.
(Other definitions for transit that I've seen before include "Passage of heavenly body" , "The process of going or passing - sic . . . . . . . gloria mundi" , "In migration" , "To pass through/across" , "Crossing - passage" .)